Preheat your oven to 350°F (175°C). Grease your baking tray.
Make your flax egg - mix together ground flaxmeal and water and let sit for 10 minutes.
In a large bowl, sift the flour and whisk together the flour, baking powder, baking soda, salt, and ground pistachios.
In a separate bowl, mix the sugar and vegan butter (room temperature). Then add flax egg, plant-based milk, lemon juice and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Pour the batter into the prepared pan and bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10 minutes. Then, use a fork or skewer to poke holes all over the top.
In a bowl or measuring cup, whisk together the condensed coconut milk, coconut milk, plant-based milk, and pistachio cream. You can also blend it together if easier.
Slowly pour the milk mixture over the warm cake, a little at a time, allowing it to soak in.
Cover the cake and refrigerate for at least 2 hours or overnight to let the flavors develop and absorb fully.
When ready to serve, whip the chilled coconut whipping cream with pistachio cream. Sift in some matcha towards the end into the fluffy cream.
Spread the whipped cream on top of the chilled cake. Garnish with chopped pistachios. Slice and serve cold!